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International board acts on Lake Ontario water levels

by jmaloni
Sat, May 11th 2013 07:00 am

In news of interest to area boaters and Lake Ontario property owners, the International St. Lawrence River Board of Control has announced its plan of maintaining current lake levels for the foreseeable future.

The board recently reviewed conditions in the Lake Ontario-St. Lawrence River system and agreed to continue to store water on Lake Ontario for future critical needs. Recently, the regulation plan was responding to below-average Lake Ontario levels by prescribing Lake Ontario outflows well below average for this time of year. As a result, since the Ottawa River freshet that began in mid-April, conditions downstream permitted only a limited amount of additional water to be stored on the lake.

The board reports that Lake Ontario is currently slightly above its plan-specified level, but below its long-term average, as are the other Great Lakes. The lake's under-discharge began when the level on Lake St. Louis at Pointe Claire downstream in the St. Lawrence River system reached a point at 1 foot lower than flood alert levels.

Currently, the board is releasing water at a rate of 7,000 cubic feet per second less than the plan-specified outflow from Lake Ontario. The board will stop storing water in Lake Ontario if the water level at Pointe Claire falls below intended levels for navigation and will resume excess storage in Lake Ontario only if the level on Lake St. Louis is at risk of exceeding its flood alert level. Property owners and boating interests on Lake Ontario are reminded this plan itself adjusts to water supplies, and a flow reduction of 7,000 cubic feet per second in one week equates to approximately 0.2 inches of water stored on Lake Ontario.

This strategy will allow the board to address uncertainty in the inflows during the freshet period. In addition, while the strategy will provide environmental and recreational benefits of higher water levels upstream on Lake Ontario, the extra water stored can also be released later in the season to benefit commercial navigation and boaters in the lower St. Lawrence River.

The level on Lake Ontario as of May 1 was 245.57 feet, 26 inches above the lower limit that applies from April 1 to Nov. 30, but 5 inches below the long-term average level for this time of year. The level on Lake St. Lawrence on May 1 was 241.83 feet, which is 3 inches above average due to lower than average outflows through the Moses-Saunders dam. The level at the Port of Montreal on May 1 was 24.51 feet, 1 inch above average.

At the board's next review session, a decision will be made whether to retain the stored water on Lake Ontario for gradual release over a possibly dry summer and fall, or to release the extra water earlier, in response to possibly wetter conditions.

Water levels on both Lake Ontario and the St. Lawrence River vary considerably from year to year depending on the weather conditions. The board urges all interests to be prepared to live within the full range of levels that have occurred.

The board, in conjunction with its staff, continues to monitor the situation carefully and is prepared to take further action as required. The board will continue to review conditions and revise the outflow strategy, if necessary. Outflow changes are posted to the board's Facebook site at www.facebook.com/ISLRBC (English) and its website at http://ijc.org/boards/islrbc/data under Lake Ontario outflow changes.

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